What do you call a house with most of the framework in place, some of the plumbing, and a few walls? More than started, but a long way from finished. That just about fits the description of what some are calling ‘the first synthetic liver.’

It’s far from being a true liver, though a few components are in place. Lead author Pedro Baptista and colleagues at Wake Forest University Baptist Medical Center (Winston-Salem, North Carolina, USA) started with an animal liver. They removed all the liver cells with a specialized detergent, leaving only the collagen ‘skeleton’ (structural material) and most of the network of blood vessels. Into this framework they introduced human liver cells of two types: immature liver cells (known as progenitor cells) and endothelial cells (surface cells) that typically line blood vessels. This constructed ‘organ’ was then placed in a bioreactor (a chambered device that provides oxygen, nutrients, and controls many environmental variables such as temperature). In about a week the scientists observed growth of cell tissue and the beginnings of liver cell function.

The technique of using ‘scaffolding’ from animal organs and filling-in with human (or animal) cells, which have a tendency to develop according to the type of cell and organ structure, has promise – if only because the resulting synthetic organ shows some of the functionality associated with the natural organ. However, so far, these bioengineered organs are rudimentary mimics. The liver, for example, is one of the most complex and critical organs in the human body. Even now its functions are only partially understood, and the work of understanding it’s fantastically complicated chemistry at the molecular level is just beginning. It is not realistic to expect that a fully functional human liver will be bioengineered in the near future.

On the other hand, producing even the crudest synthetic liver and its kin is a learning tool. At some point, relatively soon, this type of synthetic organ may also become useful for testing drugs and medical procedures.